Help... Is this a chemical?

Melody
I tested my first faint line possitive at 11 dpo. Now at 16 dpo the lines aren't getting a whole lot darker... I'm scared if this is chemical. I have all the normal symptoms of early pregnancy and I need to know if it's okay for the line to not be very dark yet... 
11 dpo...
And 16 dpo... Both tests I used FMU.